Mulching lawn mowers are known which direct the grass clippings severed by the cutting blade downwardly out of the cutting chamber to deposit such clippings in the standing grass remaining in the cut grass path. Various kinds of such mulching mowers are known. For example, mulching mowers are disclosed in U.S. Pat. Nos. 4,205,512 and 4,951,449 to Thorud, both of which are assigned to the assignee of this invention.
The mulching mowers shown in the Thorud patents have grass deflecting members or kickers within the cutting chamber to assist in the downward movement of the grass clippings. These kickers comprise angled grass deflecting surfaces that are fixed in each cutting chamber above the plane of the blade. The grass deflecting surfaces are shaped and positioned to intercept the grass clippings as they circulate inside the cutting chamber to redirect such clippings downwardly. The kickers are spaced apart around the circumference of the cutting chamber.
Other mulching mowers are known in which no kicker members are present in the cutting chamber. Instead, the cutting chamber and blade are specially shaped to effect mulching. For example, U.S. Pat. No. 3,085,386 to Slemmons discloses a mulching mower having a donut-shaped cutting chamber. A specially configured cutting blade allegedly causes the grass clippings to be cut in a radial outer portion of the cutting chamber and to be circulated upwardly and inwardly inside the cutting chamber to eventually be driven downwardly out of the cutting chamber through a radial inner portion of the chamber.
Many mulching mowers known today circulate a fairly significant halo of grass around the cutting chamber until the grass clippings are driven or fall downwardly out of the cutting chamber. Many of these mowers, including the mulching mowers shown in the above-identified patents, are powered by internal combustion engines in which power consumption is not generally an issue. Engines of sufficient horsepower are available and can generally be used to allow the grass clippings to be mulched without bogging down.
However, mowers powered by electrical motors, or lower horsepower internal combustion engines, have certain advantages, including those of reduced emissions. In the field of electrically powered mowers, various mowers have been introduced having DC motors powered by self-contained, rechargeable batteries. Some of these mowers use a generally conventionally shaped cutting chamber around the blade, namely a cutting chamber that is generally circular and closely surrounds the blade. This cutting chamber can be closed over its top and sides in a mulching mode such that the grass clippings are mulched by being driven downwardly through the open bottom side or face of the cutting chamber.
The power drain on such electrically powered mowers when they are used to mulch is significant. As a practical matter, the batteries may become discharged before the entire lawn or other turf area is mowed. This requires that the batteries be recharged before the mowing job can be finished, which is obviously inconvenient. Thus, the power consumption of such mowers during mulching, and the consequent reduction in their run time per charge, is a limitation of such a product.